The stoichimetry of proton transport by the mitochondrial respiratory chain and of oxidative phosphorylation will be reinvestigated by oxygen pulse and kinetic techniques to resolve the different values obtained by various workers. The value of the electrochemical proton gradient in submitochondrial particles will be measured and compared with the equilibrium poise of reactions in the respiratory chain to indicate whether proton transport involves conformational pumps or redox loops. The structure of the cytochrome b-c1 complex reconstituted into a liposome membrane will be studied with impermeant labels.